This invention relates to laundry pre-spotting compositions which are in the form of clear, stable, microemulsions, solutions or gels and which are suitable for the treatment of heavily soiled areas of fabrics. More particularly, the invention relates to single-phase pre-spotting compositions which are especially effective for the removal of oily stains and soils from fabrics and which are characterized by being "infinitely dilutable" with water, as herein defined, without concomitant phase separation. Thus, the removal of oily stains and soils is effected by the application of the pre-spotting composition to the generally soiled areas of the fabric which solubilizes the oily soil, followed by rinsing with water in a wash or rinse bath wherein the diluted pre-spotting compositions remains in a clear, single-phase, avoiding the attendant problem of redeposition of the oily soil on the previously cleaned fabric.
The removal of oily soils and stains from fabrics has been the focus of much attention in the laundry art. In particular, emphasis has been placed on pre-treating or pre-spotting articles of laundry which are not uniformly soiled, such as for example, shirt collars and cuffs, as a preliminary stain-removal treatment prior to regular washing. The detergent compositions which have been used and disclosed for pre-spotting have varied considerably encompassing, for example, commercial liquid laundry detergent compositions which are applied to the fabric as a pre-spotter prior to being added to the wash bath, as well as formulations intended specifically for oily soil removal which contain one or more organic solvents. While the use of aqueous liquid laundry detergents has proven successful for cleaning a wide variety of soils, the removal of oily soils, in particular, is often troublesome insofar as such liquid compositions do not generally contain a solvent especially suited for oil solubilization, such as an organic solvent. On the other hand, the known compositions which are specifically formulated for oily soil removal suffer from the fact that they are either impractical to use, or they do not avoid the problem of oily soil redeposition on the fabric in the wash or rinse bath.
The redeposition of oily soil is a problem attributable, in part, to phase separation of the pre-spotting composition containing an organic solvent when such composition becomes "infinitely" or extremely diluted with water in the wash bath. In effect, the solubilized oily soil as well as the organic solvent itself become soils to be removed from the fabric when phase separation of the pre-spotting composition occurs upon dilution. In this regard, the term "infinite dilutability" which is used herein to characterize the pre-spotting compositions of the present invention refers to the fact that the pre-spotting compositions are formulated such that when diluted with water in a ratio of at least 100 parts water to 1 part of composition, they are entirely in a clear single phase with no phase separation being present. This degree of dilutability is significant because it corresponds approximately to the dilution encountered by a pre-spotting composition when applied to a fabric which is subsequently rinsed with water, such dilution being about one hundred to one thousand-fold.
U.S. Pat. No. 4,180,472 to Mitchell et al is illustrative of a pre-treatment composition for oily stain removal which requires a multiple step operation. The patent describes a composition comprising a solvent such as an alkane in combination with a specified surfactant as an emulsifier. The described composition cannot be applied directly to the soiled fabrics, but rather, is added to the wash bath containing the items to be laundered. After oil solubilization from the soiled fabrics is effected, removal of the solvent must be carried out in a second step using a specified surfactant as a solvent stripping agent. No single-phase composition is contemplated or disclosed.
U.S. Pat. Nos. 4,093,418 and 4,178,262 to Compton et al describe laundry spot-agent compositions containing a solution of a nonionic surfactant and an isoparaffinic solvent. No water is present in the composition nor is there any indication that such compositions can be readily removed from fabrics by immersion in a wash or rinse bath without the occurence of phase separation.
British patent specification No. 1,518,676, published Jul. 19, 1978 discloses a detergent composition comprising a nonionic detergent, an organic solvent, such as, methyl laurate, and water. The percentage of organic solvent in such composition is severely restricted, however, because according to the disclosure the solvent "tends to act as a load upon the general cleaning performance of the composition". This indicates that the solvent does not remain in solution in the wash bath, but rather, is separated out and acts as a soil. In example 2 of the publication, the amount of organic solvent in the disclosed composition is 3.4%. Further, the disclosed compositions which appear to be in granular form are added directly to the wash bath, according to the examples, rather than being conveniently applied to the soiled fabrics as a pre-spotting composition.
Accordingly there remains a need in the art to provide an improved composition for oily soil removal which can be applied directly to soiled fabrics as a pre-spotter and which can be readily removed therefrom by rinsing with water.